Signal warning of insufficient sap in maple sap evaporator pan

ABSTRACT

If the amount of maple sap becomes too low in an evaporator pan during sap evaporation for producing syrup or sugar, damage may result. The present device provides an electric monitoring system which gives an audio alarm if the sap falls below a predetermined safe level in the pan.

United States Patent 1 Sipple et al.

[ Nov. 6, 1973 1 SIGNAL WARNING OF INSUFFICIENT SAP 1N MAPLE SAP EVAPORATOR PAN [76] Inventors: Lloyd H. Sipple, R.D. N0. 2,

Bainbridge, 13733; Oliver J. Hughson, 8762 Van Hoesen Rd., Clay, 13041, Robert M. Lamb, PO. Box 278, Liverpool, 13088, all f 1.

[22] Filed: Mar. 13, 1972 [21] Appl. No.: 234,262

52 us. C1. 340 244 0, 340/213 R, 73/304 R 51 1111.01. G08b 25/00 [58] Field of Search 340/244, 213.1, 213; 73/301, 304 R [56] References Cited UNITED STATES PATENTS 2,709,250 5/1955 Marrnorstone 340/2131 8/1960 Lemm et al 340/213.1 11/1969 Dotto 340/244 C X Primary-Examiner.lohn W. Caldwell Assistant ExaminerDaniel Myer Att0meyTheod0re A. Seegrist et al.

57 ABSTRACT 1f the amount of maple sap becomes too low in an evaporator pan during sap evaporation for producing syrup or sugar, damage may result The present device provides an electric monitoring system which gives an audio alarm if the sap falls below a predetermined safe level in the pan. I

1 Claim, 2 Drawing Figures PATENTEDHUY 6 m SIGNAL WARNING OF INSUFFICIENT SAP IN MAPLE SAP EVAPORATGR ?AN This invention relates to apparatus used in the condensation of maple sap for the production of syrup and sugar.

Conventional apparatus for this purpose includes an evaporator pan heated in a usual manner. Sap in the pan is boiled to drive off water'until the desired concentrate is obtained, fresh sap being supplied into the pan during the heating. In a usual apparatus the fresh sap is added to the batch by an automatic feeding device. This requires close attention. If insufficient sap is added or if the feeding device malfunctions, the sap soon becomes over concentrated and over heated, resulting in damage to the batch and in a messy clean-up job, including perhaps the destruction of an expensive pan. I

The present invention provides a simple warning system which produces an audio signal when the sap reaches a predetermined low level in the pan. Also, several pans may be protected by the same audio signal and a visual signal provided to operate for each pan. Thus the attendant does not need to give close attention to the sap level in the various pans, but needs only, when the audio signal sounds, determine which pan requires investigation.

REFERRING TO THE DRAWING FIG. 1 is a schematic showing of a two-pan apparatus, the electric circuits being in diagram; and

FIG. 2 is a structural showing of the probe used to detect when the liquid in the pan has reached its lowest predetermined safe level.

The electrical parts are housed in a metal box 5, properly grounded at 6 to the ground wire 7 of a'flexible cable having a neutral wire 8, and a hot wire 9 connected to a conventional grounded plug 10 for plugging into grounding wall outlet 11 of a usual 110 volt ac. power source. If the outlet is not itself of the grounded type, a conventional adaptor (not shown) should be used. A main power switch 12 controls the circuit.

All the electrical parts, except the manual switches and visual signal lights, are mounted inside the box 5,

the switches and lights being conveniently mounted on the box cover. A warning light 15 is connected with one terminal to the hot line 9, the other light terminal being connected to the box at 16. If the plug is in proper polarity with the outlet 1 1, light will glow when switch 12 is closed. If it does not glow, the plug should be reversed in the outlet.

A transparent glass tube 35 is connected upright to the evaporator pan 20 near its bottom through a valve 36, with the upper end of the tube open, such that, when the valve 36 is open, the sap will stand at the same level in the tube as in the pan.

The probe end of cord 31 is inserted into the upper end of tube 35 with the probe points at a desired predetermined depth, such that when the sap level falls below the probe points the warning signals will operate. The cord 31 may be wedged in the tube to retain it at the desired position.

The sap between the probe points varies in conductivity. It is more conductive when the sap is more concentrated and heated. In order to match the probe with the resistance of the solenoid 27, a high valve resistor 40 is connected in parallel with the probe points thus to insure that sufficient current will flow through the relay solenoid to trip the armature 41 away from the contacts 42 and 43 under all conditions of the sap between the probe points, and that insufficient current will flow to trip the armature when there is no sap between the probe points.

If the sap falls below the probe points, relay tension spring 45 will move the armature 41 into contact with contacts 42 and 43. In this setting of the relay, current from the hot wire 9 is traced through conductor 46, signal light 47, conductor 48, armature 41, and conductor 49 to the neutral wire 8, thus to give a visual warning signal. Current is also traced through conductor 50, an audio signal device 51, such as a bell or buzzer, a switch 52, conductor 53, armature 41, and conductor 49, to the ground wire, to give an audio warning signal.

Switch 52 may be opened to silence the buzzer.

With the arrangement described above and a relay having a coil resistance of 1250 ohms, a resistor 40 of 8000 ohms may be used.

The probe arrangement, relay and visual signal for pan 21, is the same as that for pan 20. The circuit is also the same, the two circuits being parallel. The same audio signal device 5 is used for both.

The above described warning device is designed for two evaporator pans. Any convenient number of similar warning devices may be arranged in the same mounting box, all connected in parallel to the same The apparatus illustrated is for use with two evaporator pans 20 and 21, provided with any type heating means 22 and 23, and having conventional sap feeding.

devices 24 and 25.

One part of the circuit may be traced from hot line 9 through conductor 26, relay solenoid 27, conductor 28, the detection probe 29, and conductor 30 to the neutral wire 8.

The probe 29 is conveniently provided by use of ordinary lamp cord 31 of any length suitable for mounting the box 5 in a convenient location away from the evaporator pans. The probe is formed by removing the insulation a short way from the end of the cord and separating the bared conductor ends to form probe points 32 and 33.

electric supply cable. Only one audio signal device is used, regardless of the number of evaporator pans being monitored. If any pan requires attention, the audio alarm will sound. The attendant then determines from the signal lights which pan is at fault, and he may silence the audio signal by opening the appropriate switch connecting it to the untripped relay, while he accomplishes the desired filling of the faulty pan.

We claim:

1. In a maple syrup evaporating system in which a plurality of maple sap evaporator pans are located over burners for heating sap, and in which a fluid supply of sap is provided for adding sap to each pan when the sap therein falls below a certain level, an upright open ended tube connected to each of the pans such that sap in the pan and its tube stands at the same level, two spaced apart probe points located at such a depth in each tube that if the sap falls below a predetermined safe level therein, the probe points are uncovered, an electric circuit having a current source connected to the probe points in each tube so that current passes through the sap between the points therein, said circuit including a relay for each tube having a solenoid in seto trip it when the sap falls below the probe points, an audio signal device connected in the circuit through the armature contact of any relay that is not tripped, a visual signal device for each tube connected through the armature contact of its relay when the relay is not tripped, and a switch in each of the relay circuits to disconnect the audio signal device from its circuit without disconnecting the visual signal device from its circuit. 

1. In a maple syrup evaporating system in which a plurality of maple sap evaporator pans are located over burners for heating sap, and in which a fluid supply of sap is provided for adding sap to each pan when the sap therein falls below a certain level, an upright open ended tube connected to each of the pans such that sap in the pan and its tube stands at the same level, two spaced apart probe points located at such a depth in each tube that if the sap falls below a predetermined safe level therein, the probe points are uncovered, an electric circuit having a current source connected to the probe points in each tube so that current passes through the sap between the points therein, said circuit including a relay for each tube having a solenoid in series with said points and an armature, current passing through the sap in the tube passing also through the solenoid, a resistor connected in parallel with the probe points in each tube, whereby, when the probe points are under the sap of varying concentrations and temperature of its respective evaporator pan, the current passing through the solenoid of its relay will be sufficient to trip the armature of that relay and open contacts closed by said armature, and will be insufficient to trip it when the sap falls below the probe points, an audio signal device connEcted in the circuit through the armature contact of any relay that is not tripped, a visual signal device for each tube connected through the armature contact of its relay when the relay is not tripped, and a switch in each of the relay circuits to disconnect the audio signal device from its circuit without disconnecting the visual signal device from its circuit. 